U.S. Secretary of State Mike Pompeo said Friday that he was working to address President Donald Trump’s complaints about the Iran nuclear accord, and that Trump would quit the deal unless there was “a substantive fix.”

Pompeo spoke at a news conference after a day of meetings with NATO foreign ministers, including a session with his counterparts from Britain, France and Germany — the European architects of the 2015 Iran nuclear agreement, called the Joint Comprehensive Plan of Action.

Trump has severely criticized the agreement, which was brokered by his predecessor, Barack Obama, and has said he is likely to terminate it on May 12, when a decision is due on whether to extend a suspension of sanctions against Iran.

French President Emmanuel Macron, who met with Trump in Washington earlier this week, said he expected the U.S. to quit the agreement.

“Our commitment, the United States’ commitment to the collective defense under Article 5 of the Washington Treaty remains ironclad” — Mike Pompeo

“We talked about it some today,” he said. “I am confident that that will be a topic on my trip throughout the Middle East as well, not only talking about the concerns that President Trump has expressed consistently, but talking about ways to potentially address those shortcomings, finding potential solutions to the very flaws that President Trump has identified for a long time now.”

After Brussels, Pompeo was scheduled to travel to Saudi Arabia, Jordan and Israel.

Pompeo, who previously served as Trump’s director of the Central Intelligence Agency and has also sharply criticized the Iran deal, added: “So the team is working and I am sure we will have lots of conversations to deliver what the president has made clear. Absent a substantial fix, absent overcoming the shortcomings, the flaws of the deal, he is unlikely to stay in that deal, as it is now.”

While Pompeo suggested it would be difficult to convince Trump to stay with the agreement, his comments nonetheless left open some hope for the European allies who remain strongly supportive of it. They say the deal has granted unprecedented access for international monitors, ended Iran’s nuclear weapons program and created a framework for addressing other concerns about Iran’s military and political activities throughout the Middle East.

German Foreign Minister Heiko Maas, speaking to reporters after his meeting with Pompeo about the Iran deal, called it a “good starting point.”

Pompeo, who is a graduate of the United States Military Academy at West Point, used his debut as secretary of state at NATO headquarters to spread some charm. At the outset of his news conference he emphasized Washington’s commitment to NATO’s collective defense doctrine — something that Trump as a presidential candidate and at the outset of his term had seemed to call into question by criticizing the alliance.

And in reiterating his support, Pompeo even called NATO’s treaty by its proper name.

“Our commitment, the United States’ commitment to the collective defense under Article 5 of the Washington Treaty remains ironclad,” he said.